2, 2&#39;-thiobis (5-acyl-4-alkylthiazoles)



United States Patent 2,2-TEHOBES(-ACYI-4-ALKYLTHIAZOLES) John .1.DAmico, Charleston, W. Va., assignor to Monsnnto Chemical Company, St.Louis, Mo., 2 corporation of Delaware No Drawing. Original applicationJune 21, 1952, Serial llo. 294,930. Divided and this applicationeptember 2, 1954, Serial No. 453,941

4 Claims. c1. 260-302) The present invention relates to a new class ofcompounds, namely the 2,2-thiobis(5-acyl-4-alkylthiazoles). The newcompounds may be represented by the general formula Where R and Rrepresent hydrocarbon groups.

The 5-acyl-2-mercaptothiazoles may be prepared by condensing a3-chloro-2,4-dione with ammonium dithiocarbamate. For example3-chloro-2,4-pentanedione was prepared as follows: To 845 grams (8.5moles) of 2,4- pentanedione in a suitable container provided with amechanical stirrer, condenser, dropping funnel, thermometer and icebath, 1140 grams (8.5 moles) of sulfuryl chloride was added dropwise at0-5 C. over a period of 8.5 hours. The mixture was heated at 9095 C. forminutes to complete the reaction, then cooled at C., extracted with 500ml. of 10% aqueous sodium bicarbonate, washed with water until thewashings were neutral to litmus and finally dried over sodium sulfate.Distillation of the reaction mixture under 28 mm. pressure gave 880grams of 3-chloro-2,4-pentanedione, a colorless liquid, B. P. 6063 C.

236 grams of the 3-chloro-2,4-pentanedione was added to a solution of194 grams (1.76 moles) of ammonium dithiocarbarnate in 1300 grams ofwater. The reaction mixture was stirred vigorously, the exothermicreaction causing the temperature to rise to about 52 C. and within ashort time a solid precipitated. The mixture was stirred for about 8hours and then the solids filtered off, washed with water until thewashings were neutral to litmus and finally dried in an oven at 50 C.There was obtained 226 grams or 74.4% of 2-mercapto-4-rnethyl-S-thiazolyl methyl ketone, a yellow solid, M. P. 2l0211 C. whenrecrystallized from ethyl alcohol. Analysis for nitrogen gave 8.00% andfor sulfur 37.30% as compared to calculated values for CeH7NOS2 of 8.09%nitrogen and 37.01% sulfur.

Disulfides may be prepared directly from the mercapto thiazoles byoxidation. In spite of the presence of the carbonyl group, oxidation ofthe S-acyl mercapto thiazoles with ammonium persulfate, chlorine,hydrogen peroxide, sodium hypochlorite and other oxidizing agentsconverts the S-acyl mercapto thiazoles smoothly to disulfides. Thereaction may be conveniently carried out in aqueous medium employingeither a suspension of the free mercapto thiazole or a solution of analkali metal salt thereof. Monosulfides may be prepared from thedisulfides by reaction with sodium cyanide. The disulfides take upadditional sulfur on heating therewith to form higher sulfides.Additionally, higher sulfides may be produced by reacting the 5-acylmercapto thiazoles with sulfur halides.

2,713,053 Patented July 12, 19 55 "ice The following example preparationof a disulfide.

A fine suspension of 69.3 grams (0.40 mole) of2-mercapto-4-methyl-S-thiazolyl methyl ketone in 400 ml. of water wasprepared in a one liter, three-necked flask, equipped with a mechanicalstirrer, dropping funnel, and a thermometer. To this agitated slurrythere was added dropwise 339 grams (0.44 mole) of a 30% aqueous solutionof ammonium persulfate in 30 minutes at 2530 C. The mixture was stirredfor two hours longer, the precipitate filtered oil, and dried at 50 C.The product, a tan solid, was obtained in 99.0% yield. Aftercrystallization from ethyl alcohol it melted at 92-93 C. Analysis gave8.09% nitrogen and 37.22% sulfur as compared to the calculated valuesfor 2,2'-dithiobis(5- acetyl-4-methylthiazole), C12H12N2O2S4, of 8.13%nitrogen and 37.23% sulfur. The molecular weight obtained by thefreezing point method using benzene as the solvent was 342.0; calculated344.5.

As an example of the accelerating activity of the new disulfides ascompared to the commercial accelerator 2,2'-dithiobis benzothiazolevulcanizable compositions were compounded comprising illustrates indetail the The unaetivated stocks were cured in the usual manner byheating in a press for 45 minutes at C. and those containing thediphenyl guanidine activator were cured by heating for 15 minutes at thesame temperature.

Table hgdilustot as mi y Tensile at; Ultimate Stock 5 3E 43? Brealr inElongation,

tion of lbs/1n. Percent It is intended to cover all changes andmodifications of the examples of the invention herein chosen forpurposes of disclosure which do not constitute departures from thespirit and scope of the invention.

This application is a division of co-pending application Serial No.294,930, filed June 21, 1952.

What is claimed is:

l. A compound of the structure where R and R represent alkyl groups ofless than six carbon atoms.

2. A compound of the structure where R and R represent alkyl groups ofless than six r v v 4 3. The method which comprises oxidizing amercaptan 4. The method which comprises oxidizing a mercapof thestructure tan of the structure RON\ CH3C'N\ CSH \CSH and recovering thedisulfide.

carbon atoms and recovering the disulfide. 10 No references cited

1. A COMPOUND OF THE STRUCTURE